A density functional theory investigation of the polytopal rearrangement of square-based pyramidal clusters: C5H5+, P-5(+) and Sb-5(+)

The potential energy surface associated with the reaction of interconversio n between two square-based pyramidal cations, C5H5+, has been determined by density functional theory calculations. It confirms earlier studies that p redicted a unique transition state of C-2v symmetry. The computed activatio n energy barrier (approximate to 20 kcal/mol) indicates that the reaction i s thermically feasible. Extension of this study to other isoelectronic syst ems (P-5(+) and Sb-5(+)) shows that the process is easier with heavier elem ents. (C) 2001 Elsevier Science B.V. All rights reserved.